Editing Pulsed plasma thruster (section)

== Comparison to chemical propulsion ==
The equation for the change in velocity of a spacecraft is given by the [[Tsiolkovsky rocket equation|rocket equation]] as follows:
:<math>\Delta v = v_\text{e} \ln \frac{m_0}{m_1}</math>

where:
:<math>\Delta v\ </math> is delta-v - the maximum change of speed of the vehicle (with no external forces acting),
:<math>v_\text{e}</math> is the [[effective exhaust velocity]] (<math>v_\text{e} = I_\text{sp} \cdot g_0</math> where <math>I_\text{sp}</math> is the [[specific impulse]] expressed as a time period and <math>g_0</math> is [[standard gravity]]),
:<math>\ln</math> refers to the [[natural logarithm]] function,
:<math>m_0</math> is the initial total mass, including propellant,
:<math>m_1</math> is the final total mass.

PPTs have much higher exhaust velocities than chemical propulsion engines, but have a much smaller fuel flow rate. From the Tsiolkovsky equation stated above, this results in a proportionally higher final velocity of the propelled craft. The exhaust velocity of a PPT is of the order of tens of km/s while conventional chemical propulsion generates [[thermal velocity|thermal velocities]] in the range of 2–4.5&nbsp;km/s. Due to this lower thermal velocity, chemical propulsion units become exponentially less effective at higher vehicle velocities, necessitating the use of electric spacecraft propulsion such as PPTs. It is therefore advantageous to use an electric propulsion system such as a PPT to generate high interplanetary speeds in the range 20–70&nbsp;km/s.

[[National Aeronautics and Space Administration|NASA's]] research PPT (flown in 2000) achieved an exhaust velocity of 13,700&nbsp;m/s, generated a [[thrust]] of 860&nbsp;μN, and consumed 70{{nbsp}}W of electrical power.<ref name = NASAPPT/>